This invention relates to a heavy duty suspension system such as for a motorhome, and more particularly, the invention relates to a trailing arm suspension system.
Various types of suspension configurations have been used for heavy duty applications. For drive axles, the suspension geometry affects the pinion angle. Pinion angle is the angle between the axle input shaft axis and the drive shaft axis. It is desirable to have as little pinion angle as possible to reduce wear. Additionally, it is desirable to have equal angles between the driveshaft axis and the axle input shaft axis and the transmission output shaft axis to balance the forces on the yokes.
Trailing arm suspensions have been employed for heavy duty applications such as for motorhomes. An axle may be rigidly or pivotally secured to the trailing arm. For drive axle trailing arm suspensions, such as for motorhome applications, the pinion angle of the axle is frequently defined by an upper attachment member. The upper attachment member and trailing arm defines the pinion angle during the operation of the suspension. One suspension configuration has employed a rod arranged longitudinally between the frame and the axle to define the pinion angle. This configuration additionally employs a lateral rod connected between the axle and the frame. Such a configuration of rods has the undesirable effect of moving the axle input shaft along an arcuate path in a vertical lateral plane during suspension operation. Instead of the rods, the upper attachment member may be defined by a triangular plate. The apex of the plate is pivotally attached to the axle and the side opposing the apex is attached between opposing frame rails. However, the plate lacks sufficient structural integrity as an upper attachment member and is difficult to install and service. Therefore, what is needed is an improved heavy duty trailing arm suspension system.